Forest Laboratories has been boosted by positive data from a late-stage trial of a once-daily version of its Alzheimer’s disease drug Namenda.

The firm, which currently markets a twice-daily immediate-release formulation of the drug, announced results of a 24-week Phase III study of Namenda (memantine) which evaluated a 28mg dose of extended-release Namenda in 677 patients with moderate-to-severe Alzheimer’s currently treated with a cholinesterase inhibitor. The data showed that patients receiving long-acting memantine experienced statistically significant benefits in cognition and clinical global status compared to placebo.

Ivan Gergel, senior vice president of scientific affairs at Forest, claimed that "the higher dosage and once-daily formulation will provide patients with the efficacy and tolerability expected from Namenda, in a more convenient once-daily form." He added that based on the results, the firm will pursue a New Drug Application for the new version and additional data from the Phase III trial are expected to be presented later this year.

Namenda, an N-methyl-D-aspartate (NMDA) receptor antagonist, is Forest’s second-biggest earner after the antidepressant blockbuster Lexapro (escitalopram). Sales for the fourth quarter reached $218.7 million during the quarter, up 26%, but the spectre of generic competition looms. Last month the company and Germany’s Merz Pharma (which licensed the drug to Forest in 2001) filed patent infringement lawsuits against Teva, Barr Laboratories and Cobalt, plus the Indian drugmakers Lupin, Orchid and Wockhardt, among others.

Forest believes its Namenda patent expires in April 2010, and it has applied for an extension which, if granted, would give coverage up to September 2013.